In the simplest of explanations, It creates power by producing extra electrons than what was thrown into the reaction originally. This doesn’t relate to heat boiling water, just as much as it does relate to energy being simply harnessed. No temperature involved.

Usually the factors involved are fuels that differ from what you might think of as fuels like gasoline or diesel. helium-3 and deuterium are cold fusion fuels, and energy reactions caused by electromagnetic forces and plasma from the ionized fuels. The magnetic fields cause particles to move around at such an incredible rate that it’s almost like a small particle collider, until they are quickly, violently, slammed together. This both in theory and as of recently, and literally can create extra electrons and excited particles.

To use this as a feasible method of making energy and using it on real world applications, you would need to be generating a lot more than what we can currently generate. But again, as of recently, this is possible.